Chemische Technologie der Materialsynthese, Julius-Maximilians-Universität Würzburg, Röntgenring 11, 97070 Würzburg, Germany.
Département de Chimie, Université de Montréal, 1375 Avenue Thérèse-Lavoie-Roux, Montréal, Québec, H2V-03B, Canada.
Dalton Trans. 2021 Nov 23;50(45):16528-16538. doi: 10.1039/d1dt00868d.
In this study, we report two dinuclear Ru(II) complexes C1 and C2 and compare them to their mononuclear analogues Ref1 and Ref2. The dinuclear species exhibit a much stronger absorption, longer excited-state lifetimes and higher luminescence quantum yields than the mononuclear complexes. In addition, C1 and C2 are easier to reduce. An estimation of the driving forces for the electron transfer processes relevant to photocatalytic hydrogen evolution suggests that C1 and Ref2 possess similar activity as photosensitizer (PS). Yet, the improved photophysical properties of C1 make it a more promising candidate for hydrogen evolution. In hydrogen evolution experiments, C1 indeed exhibits increased activity as PS, however, the catalytic system loses its activity after only a few hours. C2 is less active than the mononuclear complexes despite its superior photophysical properties. This observation is attributed to a lack of driving force for the electron transfer towards the catalyst. Further studies of the dinuclear complex C1 show that it is indeed the PS, which decomposes under the catalytic conditions, presumably due to the electron transfer towards the catalyst being the rate-limiting step.
在这项研究中，我们报告了两个双核 Ru(II) 配合物 C1 和 C2，并将其与单核类似物 Ref1 和 Ref2 进行了比较。双核物种表现出比单核配合物更强的吸收、更长的激发态寿命和更高的荧光量子产率。此外，C1 和 C2 更容易还原。对与光催化析氢相关的电子转移过程驱动力的估计表明，C1 和 Ref2 具有相似的光致剂 (PS) 活性。然而，C1 改进的光物理性质使其成为更有前途的析氢候选物。在析氢实验中，C1 确实作为 PS 表现出增加的活性，然而，催化体系在几个小时后就失去了活性。尽管 C2 具有优越的光物理性质，但它的活性却低于单核配合物。这一观察结果归因于向催化剂转移电子的驱动力不足。对双核配合物 C1 的进一步研究表明，确实是 PS 在催化条件下分解，这可能是由于电子向催化剂的转移是限速步骤。
